This disclosure relates to electrochemical cell systems, and, more particularly, to a gas liquid phase separator in which at least two control valves provide drainage of the phase separator at corresponding flow rates.
Electrochemical cells are energy conversion devices, usually classified as either electrolysis cells or fuel cells. Proton exchange membrane electrolysis cells can function as hydrogen generators by electrolytically decomposing water to produce hydrogen and oxygen gases. Referring to FIG. 1, a section of an anode feed electrolysis cell of the prior art is shown generally at 10 and is hereinafter referred to as xe2x80x9ccell 10.xe2x80x9d Reactant water 12 is fed into cell 10 at an oxygen electrode (anode) 14 to form oxygen gas 16, electrons, and hydrogen ions (protons) 15. The chemical reaction is facilitated by the positive terminal of a power source 18 connected to anode 14 and the negative terminal of power source 18 connected to a hydrogen electrode (cathode) 20. Oxygen gas 16 and a first portion 22 of the water are discharged from cell 10, while protons 15 and a second portion 24 of the water migrate across a proton exchange membrane 26 to cathode 20. At cathode 20, hydrogen gas 28 is removed, generally through a gas delivery line. The removed hydrogen gas 28 is usable in a myriad of different applications. Second portion 24 of water is also removed from cathode 20.
An electrolysis cell system may include a number of individual cells arranged in a stack with reactant water being directed through the cells via input and output conduits formed within the stack structure. The cells within the stack are sequentially arranged, and each one includes a membrane electrode assembly defined by a proton exchange membrane disposed between a cathode and an anode. The cathode, anode, or both may be gas diffusion electrodes that facilitate gas diffusion to the proton exchange membrane. Each membrane electrode assembly is in fluid communication with flow fields adjacent to the membrane electrode assembly, defined by structures configured to facilitate fluid movement and membrane hydration within each individual cell.
The portion of water discharged from the cathode side of the cell, which is entrained with hydrogen gas, is fed to a phase separator to separate the hydrogen gas from the water, thereby increasing the hydrogen gas yield and the overall efficiency of the cell in general. The removed hydrogen gas may be fed either to a dryer for removal of trace water, to a storage facility, e.g., a cylinder, a tank, or a similar type of containment vessel, or directly to an application for use as a fuel.
While existing electrolysis cell systems are suitable for their intended purposes, there still remains a need for improvements, particularly regarding the management of the separation of the hydrogen gas from the water. Furthermore, a need exists for, improved control of the level of the water in the phase separator during the operation of the cell system.
The above-described drawbacks and disadvantages are alleviated by a gas/liquid phase separator for an electrochemical cell system in which the phase separator has improved pressure control capability. The phase separator includes a fluid inlet, a vapor outlet, a liquid outlet, and first and second valves disposed in fluid communication with the liquid outlet. Both valves are controllable in response to the liquid level in the phase separator as well as the hydrogen system pressure. Both valves are further disposed in parallel flow configuration with each other.
A method of controlling a liquid level in the phase separator includes sensing an amount of liquid in the phase separator, sensing the hydrogen system pressure, and selectively opening a valve disposed in fluid communication with the phase separator to drain the liquid.
The above discussed and other features will be appreciated and understood by those skilled in the art from the following detailed description and drawings.